There have been practically used micro test chips, micro analysis chips or an apparatus called μTAS (Micro Total Analysis Systems) (hereinafter, these are called microchips), wherein a fine structure, a flow path or a circuit is formed on a substrate member by using fine processing technology, and chemical reactions, separation and test such as analysis of a specimen such as a nucleic acid, a protein and blood are conducted in a minute space. Such a microchip has advantage of reducing used amounts of specimens and reagents and discharge amount of waste fluid and achieving a space-saving, portable, and inexpensive analysis system. Recently, it has been required to especially develop resin microchips which are low-cost and relatively easy to waste.
A microchip is manufactured by attaching two substrate members to each other, at least one of which has a fine structure. The fine structure on the substrate member is formed as a flow path groove, a puddle and a through-hole which penetrates the substrate member in the thickness direction. In such microchip, a specimen or a reagent is injected through the through-hole and reaction is made in the flow path groove or the puddle to perform a test.
Among the substrate members of such microchip, the substrate member having the fine structure including the through-hole is produced by injection molding. As an injection molding method of a product having the through-hole, the patent document 1 discloses a technique in which a pin is inserted into an insert of a movable mold piece, the pin is biased toward the movable mold piece by a spring, the tip of the pin sticks to the movable mold piece and injection molding is performed to prevent the generation of flash. As another injection molding method, there is also a method of inserting pins from both sides of the fixed and movable mold pieces to abut the two pins with each other at the central portion of the space in which resin is injected.
On the other hand, though there are various manufacturing methods of a mold, an electroformed mold having a high-accuracy transcription is appropriate for producing a fine structure such as a microchip. The electroformed mold is manufactured by producing a base die at first and performing electroforming on the base die so that metal is electrodeposited thickly. Thereafter, the electrodeposited material is released from the base die to be used as an electroformed mold.
As a material of the mold, nickel, nickel alloy and the like are used. For example, the patent document 2 discloses an electroformed mold obtained by forming an electroplated layer of nickel or cobalt on a base die surface at first and forming a nickel alloy electroformed layer thereon. Further, the patent document 3 discloses a technique of removing the electroplated layer of nickel or cobalt which was formed first by nitric acid aqueous solution. Though having good releasability from the base die, the electroplated layer of nickel or cobalt formed first is soft, and thus the patent document 2 leaves the electroplated layer of nickel or cobalt at the surface be worn out due to repeated use of the mold, whereas the patent document 3 removes the electroplated layer of nickel or cobalt at the surface to expose the hard nickel alloy electroformed layer on the surface.